JP2952063B2 - X-ray mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mask used for X-ray lithography for manufacturing semiconductors.

[0002]

2. Description of the Related Art Conventionally, various methods have been used as lithography processing methods for electronic devices such as ICs and LSIs. Among them, X-ray lithography is based on properties such as high transmittance and single wavelength inherent in X-rays. It has many advantages over conventional lithography methods using visible light or ultraviolet light, and is attracting attention as a powerful means of quarter-micron lithography. In general, an X-ray mask used for X-ray lithography comprises a Si wafer substrate 21 having a thickness of 0.4 to 2 mm, an X-ray transmission film 22, and an X-ray absorber 23, as shown in the schematic cross-sectional view of the mask shown in FIG. ing. The Si substrate is etched in a circular or polygonal shape at the center, and after the etching, it becomes a freestanding X-ray transmitting film. The X-ray absorber is formed as a circuit pattern on this free-standing film. An X-ray absorber 24 is formed outside the circuit pattern in a solid shape to prevent transmission of X-rays.

[0003]

In the X-ray lithography using the X-ray mask, the exposure is usually performed in a step-and-repeat manner. At this time, multiple exposure becomes a problem. On the outside of the circuit pattern 23 of the X-ray mask, an X-ray absorber 24 having the same thickness as the inside circuit pattern is formed in a solid shape to prevent transmission of X-rays. However, an X-ray absorber having the same thickness as the circuit pattern cannot completely absorb X-rays,
More than 10% are transmitted. When exposure is performed in a step-and-repeat manner, transmission X-rays of several to several tens of percents pose a problem. That is, multiple exposure. When exposure is performed in a step-and-repeat manner, as shown in FIG.
2 is exposed by X-rays transmitted through the absorber 24.

In particular, the hatched portion 33 is exposed to triple exposure. This exposure causes a decrease in line width accuracy and a decrease in film thickness, which is a major problem. As a method for solving this, it has been proposed to increase the thickness of the absorber outside the circuit pattern or to provide an aperture separately from the mask, but the former increases the thickness of the absorber. This makes it difficult to control the internal stress of the absorber, increases the positional distortion of the mask pattern, and the latter makes it very difficult to position the aperture and complicates the mechanism of the apparatus (particularly). Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, to prevent multiple exposure of X-rays, and to transfer X-rays with high precision by X-ray exposure. It is to provide a mask.

[0005]

The above objects are achieved by the present invention described below. That is, the present invention relates to an X-ray mask having an X-ray transmission film, an X-ray absorber, and an X-ray transmission film support, wherein the X-ray transmission film and the X-ray transmission film support have a boundary portion.
An X-ray mask characterized in that a multiple exposure preventing film is formed on both sides only in a limited area.

[0006]

According to the present invention, the X-ray transmitting film of the X-ray mask and the X-ray
By forming a multiple exposure prevention film on both sides limited to the vicinity of the boundary with the X- ray transmission film support, it is possible to prevent multiple exposure of X-rays and to prevent the master pattern generated by installing the multiple exposure prevention film. Positional distortion can be reduced. Further by using a gold plating film on both sides forming the multiple exposure prevention film can and substantially eliminate this pattern positional distortion due to multiple exposure prevention film formation.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing one embodiment of the X-ray mask according to the present invention. In FIG. 1, reference numeral 1 denotes an X-ray transmitting film support, 2 denotes an X-ray transmitting film, 3 denotes an X-ray absorber, and 4 denotes a multiple exposure preventing film.

Embodiment 1 FIG. 4 shows an example of a manufacturing process of the X-ray mask of the present invention. First, as shown in FIG. 4A, SiN, SiC, and B are placed on a substrate (X-ray permeable film support 41) made of Si, quartz, or the like.
An X-ray transmission film 42 of N or the like is formed to a thickness of 1 to 3 μm by a CVD method or a sputtering method. Next, as shown in FIG. 4B, an exposure window is formed by performing a wet etching process on the back surface of the X-ray permeable film support 41. Next, FIG.
As shown in (c), the plating electrode 43 is formed by a method such as EB or resistance heating evaporation. At this time, the size of the plating electrode on the back side is outside the circuit pattern on the front side.
Next, as shown in FIG. 4D, a resist pattern 44 is formed on the plating electrode 43 by a method such as electron beam exposure. Also at this time, the position of the resist pattern is adjusted to the plating electrode on the back surface. In other words, the outside of the circuit pattern is aligned front and back. Subsequently, as shown in FIG. 4E, gold plating 45 is performed simultaneously on the front and back surfaces, and the resist and the base of the plating are peeled off to obtain an X-ray mask of the present invention. The gold plating may be performed on both sides sequentially instead of simultaneously, but in this case, the film thickness is made as uniform as possible.

Embodiment 2 FIG. 5 shows another example of the manufacturing process of the X-ray mask of the present invention.
First, as shown in FIG. 5A, an X-ray permeable film 52 such as SiN, SiC, or BN is formed on a substrate (X-ray permeable film support 51) made of Si, quartz, or the like to a thickness of 1 to 3 μm by CVD or It is formed by a sputter method or the like. Next, as shown in FIG. 5B, a plating electrode 53 is formed at the position where the multiple exposure preventing film is formed. Next, as shown in FIG. 5C, an X-ray absorber layer 54 made of WN _x , Ta, W, or the like is formed on the X-ray transmission film 52 by a sputtering method, a CVD method, or the like. Next, as shown in FIG. 5D, a resist pattern 55 is formed on the X-ray absorber by a method such as electron beam exposure. Next, as shown in FIG. 5E, an X-ray absorber pattern 56 is formed using the resist pattern 55 as an etching mask, and the resist is removed after etching. Next, as shown in FIG.
Is formed on the back side of the position outside the circuit pattern. Next, as shown in FIG. 5 (g), gold plating is simultaneously or sequentially performed on the plating electrodes to obtain an X-ray mask of the present invention. Note that the present invention is not limited to the above-described embodiment, and various modifications are possible.

[0010]

As described above, according to the X-ray mask of the present invention, the multiple exposure, which has been a major problem in the past, can be eliminated and the line width can be controlled accurately. Furthermore, since the same multiple exposure prevention film is formed on both surfaces of the X-ray transmission film, the internal stress generated by the formation of the multiple exposure prevention film can be canceled by itself without affecting the position of the circuit pattern. A multiple exposure prevention film can be formed. Therefore, highly accurate circuit pattern transfer by X-ray exposure becomes possible.

[0011]

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an X-ray mask of the present invention.

FIG. 2 is a sectional view schematically showing a conventional X-ray mask.

FIG. 3 is a diagram illustrating multiple X-ray exposure.

FIG. 4 is a diagram showing one example of a manufacturing process of the X-ray mask of the present invention.

FIG. 5 is a diagram showing another example of the manufacturing process of the X-ray mask of the present invention.

[Explanation of symbols]

 1, 21, 41, 51: X-ray permeable film support 2, 22, 42, 52: X-ray permeable film 3, 23, 54: X-ray absorber 4: Multiple exposure preventing film 31: X-ray required exposure area 32 : X-ray exposure area 33: Multiple exposure area 43: Plating electrode 44, 55: Resist pattern 45: Plating film 53: Plating electrode 56: X-ray absorber pattern 57: Plating film

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01L 21/027 G03F 1/16

Claims (2)

(57) [Claims] 1. An X-ray mask having an X-ray transmission film, an X-ray absorber and an X-ray transmission film support, wherein the X-ray transmission film and the X-ray transmission film
An X-ray mask characterized in that a multiple exposure preventing film is formed on both sides of the film only in the vicinity of the boundary with the X-ray transmitting film support . 2. The X-ray mask according to claim 1, wherein the multiple exposure preventing film is a gold plating film.